Color liquid crystal display devices with cholesteric liquid crystals are particularly well suited for reflective color LCD display devices. Such color liquid crystal display devices are known in a multiplicity of embodiments. Relevant reference is made, for example, to printed documents U.S. Pat. No. 5,493,430 B, US 2004/0239830 A1 and US 2004/0041163 A1. In these known color liquid crystal display devices, the various colors are represented by mixing the three primary colors red, green and blue. In consequence, three separate pixels in the above three primary colors, which are arranged in one plane, are needed for representing a single color pixel. This limits the resolution of the color liquid crystal display device.
From U.S. Pat. No. 6,791,512 B1, a color LCD display with two liquid crystal layers arranged behind one another is known. In this arrangement, the individual primary color pixels are arranged next to one another in one liquid crystal layer. The second liquid crystal layer is only used for representing primary color pixels from the first liquid crystal layer either offset or not offset. This results in a sharper display.
From printed documents U.S. Pat. Nos. 6,377,321 B1, 6,654,080 B1 and US 2005/0036077 A1, a color liquid crystal display device is in each case known which have two liquid crystal layers arranged behind one another. One liquid crystal layer in this arrangement is used for reflecting visible light and the other liquid crystal layer is used for reflecting IR light. This does not result in an improvement in the resolution.
From JP 10-054996 A, a color liquid crystal display device is known which has a first and a second cholesteric liquid crystal layer which are arranged behind one another in the direction of viewing. The first cholesteric liquid crystal layer is arranged between a first and a second substrate and the second cholesteric liquid crystal layer is arranged between the second and a third substrate. In the first liquid crystal layer, green and red primary color pixels are arranged alternately and in the second liquid crystal layer blue and green primary color pixels are arranged alternately.
A further disadvantage of known color LCD displays consists in that their legibility is unsatisfactory in bright sunlight or in any other bright environment.